The question of differences between iodine numbers of coconut oil and of the corresponding soapstock fatty acids

Summary Experiments have been made on coconut oil from pure endosperm, pure testa, and normal mixtures of the two. These experiments have shown that the spread in iodine value between refined coconut oil and the fatty acids found on the corresponding soapstock are greater than can be accounted for by the proportion of testa oil present in extracted whole crude oils. Furthermore the iodine value of the free fatty acid fraction of pure endosperm oils was found to be higher than that of the combined fatty acids in the same oils by an amount which varied inversely as the degree of hydrolysis which had occurred in the oil. From this it appears that preferential hydrolysis plays an important part in the production of coconut oil soapstock having higher iodine values than those of the corresponding refined oils. Attention is also called to some European publications which deal with this question and to the possibility that molds may be involved through their ability to decompose short chain acids to ketones.     

Thermal and mechanical properties of LaCoO3 and La0.8Ca0.2CoO3 perovskites

In this work, the thermal and mechanical properties such as coefficient of thermal expansion, strength, Young's modulus and fracture toughness of LaCoO₃ and La_0.8Ca_0.2CoO₃ perovskites have been studied, as well as slow crack growth of La_0.8Ca_0.2CoO₃. The mechanical performance of the two cobaltites have been evaluated in terms of their ferroelastic hysteresis properties such as non-symmetry in bending of both stress and strain distributions, non-linear deformation upon applied load from the arbitrary low stresses, and ferroelastic toughening.     

Surface features of exfoliated graphite/bentonite composites and their importance for ammonia adsorption

Commercial graphite intercalated with sulfuric or nitric acid was exfoliated by rapid heating at 800 °C, homogenously mixed with bentonite water suspension and then dried at 120 °C. Dynamic ammonia adsorption was then measured on the prepared samples, the as received intercalated graphite, the expanded graphite, and the as received bentonite. The surface of the materials before and after exposure to ammonia was characterized using adsorption of nitrogen, XRD, SEM, FTIR, TA, and potentiometric titration. The results showed that mixing exfoliated graphite with clay leads to formation of layered composites on which enhanced amount of ammonia is retained. It is likely there are three types of active sites for ammonia adsorption. The first group consists of acidic functional groups formed on the edges of graphite flakes during exfoliation. The second groups are Brønsted or Lewis acidic centers of clay origin, and the third category includes unique features of the composite structure and chemistry. When a composite is formed metal cations from the clay interlayer space react with carboxylic groups of graphite flakes, as a result, the layer charge has to be balanced by additional adsorption of ammonia, which results in an enhancement in the performance of these materials as ammonia removal media.     

Role of phosphorus in carbon matrix in desulfurization of diesel fuel using adsorption process

Adsorptive removal of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) from model diesel fuel with 20 ppmw total concentration of sulfur was investigated on polymer-derived carbons with incorporated heteroatoms of oxygen, sulfur and phosphorus. The materials before and after exposure to model diesel fuel were characterized using adsorption of nitrogen, thermal analysis, potentiometric titration, XPS and elemental analysis. The selectivities for DBT and DMDBT adsorption were calculated with reference to naphthalene. The results indicated that the presence of phosphorus, especially in the form of pyrophosphates and P₂O₅, increases the capacity and selectivity for removal of dibenzothiophenes. It also affects the adsorption mechanism. Phosphorus suppresses oxidation reactions of DBT and DMDBT. Owing to a possible location of bulky phosphorus groups in pore with sizes between 1 and 3 nm thiophenic molecules are strongly adsorbed there via dispersive forces. Acidic environment also enhances adsorption via acid–base interactions. Physical adsorption mechanism and stability of surface make these carbons attractive candidates for thermal regeneration.     

Removal of antibiotics from water using sewage sludge- and waste oil sludge-derived adsorbents

Sewage sludge- and waste oil sludge-derived materials were tested as adsorbents of pharmaceuticals from diluted water solutions. Simultaneous retention of eleven antibiotics plus two anticonvulsants was examined via batch adsorption experiments. Virgin and exhausted adsorbents were examined via thermal and FTIR analyses to elucidate adsorption mechanisms. Maximum adsorption capacities for the 6 materials tested ranged from 80 to 300 mg/g, comparable to the adsorption capacities of antibiotics on various activated carbons (200-400 mg/g) reported in the literature. The performance was linked to surface reactivity, polarity and porosity. A large volume of pores similar in size to the adsorbate molecules with hydrophobic carbon-based origin of pore walls was indicated as an important factor promoting the separation process. Moreover, the polar surface of an inorganic phase in the adsorbents attracted the functional groups of target molecules. The presence of reactive alkali metals promoted reaction with acidic groups, formation of salts and their precipitation in the pore system.     

Effects of surface chemistry on the reactive adsorption of hydrogen cyanide on activated carbons

Two activated carbons of different origins were modified by heating at 950 °C either with or without previous urea impregnation. The treatment causes changes in surface chemistry and porosity. The materials obtained were used as adsorbents for hydrogen cyanide in dry air at ambient conditions. The samples before and after adsorption were characterized using nitrogen adsorption, potentiometric titration, elemental analysis and thermal analysis. On selected samples extraction was carried out to identify surface reaction products soluble in alcohols. The results indicated differences in the amount adsorbed and the products of surface reactions on specific surface features. The presence of nitrogen incorporated in the carbon matrix leads to an enhanced performance owing to the basic environment and the ability of the surface to activate oxygen. These lead to complex surface reactions in which the derivatives of hydrogen cyanide form oxamide, and are incorporated in the carbon matrix, or are deposited as the bulky insoluble polymers of paracyanogen on the surface. The reactions mainly occur in pores with sizes between 10 and 20 Å where the functional groups can be present and HCN, or its derivatives, and water can take part in the reactions.     

SOPHIA: an interactive cluster-based retrieval system for the OHSUMED collection.

The ability to perform an exploratory search and retrieval of relevant documents from a large collection of domain-specific documents is an important requirement both in the field of medicine and other areas. In this paper, we present a unsupervised distributional clustering technique called SOPHIA. SOPHIA provides a semantically meaningful visual clustering of the document corpus in conjunction with an intuitive interactive search facility. We assess the effectiveness of SOPHIA's cluster-based information retrieval for the MEDLINE testset collection known as OHSUMED.     

Surface properties of porous carbons obtained from polystyrene-based polymers within inorganic templates: role of polymer chemistry and inorganic template pore structure

Three inorganic adsorbents were applied as templates to produce porous carbons from polystyrene-based organic polymers. As matrices, amorphous silica gel, mesoporous alumina and microporous zeolite 13X were used. Organic precursors were polystyrene sulfonic acid (co-maleic acid) sodium salt and polystyrene co-maleic acid isobutyl/methyl mixed ester. The impregnated templates were carbonized at 800 °C. After removal of inorganic matrices porous carbons were obtained. Materials were characterized by adsorption of nitrogen, thermal analysis, potentiometric titration and SEM. Owing to the template carbonization, highly mesoporous carbons were obtained (S_BET up to 1500 m²/g, V_t up to 3 cm³/g) with majority of pores with sizes between 20–200 Å. Although the carbons were not replicas of their matrices, the carbonization within the confined space with utilization of self-released pore formers resulted in unique carbonaceous materials with very acidic surface. That acidity is linked to either exothermic effect of sodium reactivity with moist air or susceptibility for air oxidation of small graphene layers formed in the confined pore space.     

Graphite Oxides Obtained from Porous Graphite: The Role of Surface Chemistry and Texture in Ammonia Retention at Ambient Conditions

Graphite oxides (GO) synthesized using Brodie and Hummers methods are tested for ammonia adsorption at ambient conditions with different contents of water in the system. Surface characterization before and after exposure to ammonia is performed using XRD, FTIR spectroscopy, potentiometric titration, thermal analysis, adsorption of nitrogen, and XPS. Oxidation of the same porous graphite using two methods results in materials with different textural and chemical features. On GO obtained using the Brodie method mainly epoxy and carboxylic groups are present whereas on the GO obtained using the Hummers method chemisorbed oxygen is also found. The contribution of the carboxylic groups in the latter material is greater. It also contains sulfur either in sulfones or as residual sulfuric acid. Ammonia is adsorbed either via reaction with surface groups or dissolution in water. The former is responsible for strong adsorption. The evidence of the catalytic effect of the carbon surface on activation of oxygen leading to surface oxidation is also observed.